My car was running sweet. Drove 20miles to work all good. Moved the car from one car park to the other and it was idling lower than normal, about 800 rpm (normally about 950), also missing slightly. I drove it home and ran on full boost from some of the way, it drove fine and pulled very well. Got home and still the idle was poor. Started her today and the idle was down to 600rpm once warmed up and almost cutting out, defo missing on one side. Drove about 200m to turn the car round and it drove fine again.

 

Not changed anything at all since it was running properly. I think can hear a hissing around the brake booster pipes (which i did change about a month ago), but the brakes and clutch work fine.

 

Oh yeah when it was struggling to tickover the vaccum was reading low, much lower than normal on my boost controller.

 

oh and no errors on the ecu

 

Vaccum leak i take it? Anyone else got any input?

Finished putting my new seats in and rebuilt a motor on one, all good.

 

Still got the B@*ted vaccum leak and i cant find it! My vaccum is way low and its messing with the a/f mix.

 

Can a boost leak detector find vaccum leaks as well? Can anyone lend me one, please!!!!

Hi. I have a vacuum gauge and a conzult. I'm a technician by trade and own a Z32. Could come and have a look at your running fault if you like? I live in Macclesfield which is about an hour away.

Thanks for the offer. I'm 99% sure its a leak as can hear it hissing and my vaccum is well low on my gauge and boost controller, about 30% lower than normal. I have a greddy infometer which is a bit like a conzult and it shows the a/f mix is much higher than normal, confiming lack of air. 0 ecu errors.

O2 sensors all working fine etc.

 

Its just really annoying as i cant seem to find the offending pipe. :headvswal

 

I might try making a leak detector from a coke bottle and car tyre valve, pump air through it to find the leaking pipe.

 

I know this works with boost leaks, but can anyone tell me if it works with vaccum leaks?

 

The car still boosts fine

can anyone tell me if it works with vaccum leaks?

 

 

I'm pretty sure it does mate

Thats my next thing then, will make one, ta

Yeah boost leak/vac leak are both the same thing, just the direction of the leaking air is different :)

 

Just because the vacuum is lower, it doesn't necessarily mean that there is a leak - the engine revs are a lot lower so the engine isn't drawing as much air, so the vacuum is bound to be lower under your conditions anyway ;)

 

Check the small vac hose under the pass side TB boost hose - these have a habit of coming off, also the one on the drivers side TB pointing towards the inner wing. Check the balance bar is bolted down properly and that the o-rings are properly seated.

 

If its missfiring then you need to check which cylinder isn't firing and whether its spark or fuel related. With the engine running, pull each coil pack connector in turn, when there is no drop in engine revs when one is pulled - this is the missfiring cylinder. To check for a spark take the coilpack out, place a spare plug in it and rest the thread of the plug on the plenum - crank the engine and check the plug is sparking. If not check the PTU connectors and also try a known good coilpack. If it IS firing then check the injector connector for that cylinder - usually a good prod with a long screwdriver moves the connector contacts enough to get a connection again without removing the plug...

Cheers Andy will check those, my car drives and boosts fine tho, prob is just at idle

 

The hissing noise is coming from below the brake booster pipes i think

hi mate i beleive i have the same problem... which pipe did you end up having to change?

 

darren!

Its the booster itself i rekon. Cold weather killing the seals in them.

 

Easy way to find out is dissconnect the vac line from the balance bar and block it off. Its the far left one on the balence bar (rhd car), it has an L shaped one way valve, block it off before the valve.

 

If the prob with your car (rough idle and low vac) is then fixed you know the leak is in the clutch booster system.

 

What I then did was to connect the vac line back up and disconnect it from the booster itself. Block it here and if its still fixed you know its the booster. If it runs like poo again you know its a leak somewhere in the vac system.

 

The vac line to the booster you can see, just under the clutch master cyclinder. It just pulls off.

 

Im now looking for a new booster or an na pedal conversion

oh ok, i drive an auto

:headvswal

Still think its a spark plug/PTU/injector problem tbh

well for me it cant be, i've changed the plugs, checked all the coilpacks, injector resistance etc and recently got a brand new S2 ptu, i get this weird hissing tho. initially i thought its an exhaust gasket but when i changed oil yesterday i had a good look and its not that.

 

prob some other pipe somewhere!!!

make a boost leak detector mate.

 

i used a broken maf, a bit of wood, car valve from a mountain bike innertube, and loads of sealant.

 

i found about 3 air leaks which are now all sealed :)